diff options
author | Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 12:17:53 -0700 |
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committer | Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 15:44:42 -0700 |
commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/arm/nwfpe/README.FPE | |
parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/Documentation/arm/nwfpe/README.FPE')
-rw-r--r-- | kernel/Documentation/arm/nwfpe/README.FPE | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/kernel/Documentation/arm/nwfpe/README.FPE b/kernel/Documentation/arm/nwfpe/README.FPE new file mode 100644 index 000000000..26f5d7bb9 --- /dev/null +++ b/kernel/Documentation/arm/nwfpe/README.FPE @@ -0,0 +1,156 @@ +The following describes the current state of the NetWinder's floating point +emulator. + +In the following nomenclature is used to describe the floating point +instructions. It follows the conventions in the ARM manual. + +<S|D|E> = <single|double|extended>, no default +{P|M|Z} = {round to +infinity,round to -infinity,round to zero}, + default = round to nearest + +Note: items enclosed in {} are optional. + +Floating Point Coprocessor Data Transfer Instructions (CPDT) +------------------------------------------------------------ + +LDF/STF - load and store floating + +<LDF|STF>{cond}<S|D|E> Fd, Rn +<LDF|STF>{cond}<S|D|E> Fd, [Rn, #<expression>]{!} +<LDF|STF>{cond}<S|D|E> Fd, [Rn], #<expression> + +These instructions are fully implemented. + +LFM/SFM - load and store multiple floating + +Form 1 syntax: +<LFM|SFM>{cond}<S|D|E> Fd, <count>, [Rn] +<LFM|SFM>{cond}<S|D|E> Fd, <count>, [Rn, #<expression>]{!} +<LFM|SFM>{cond}<S|D|E> Fd, <count>, [Rn], #<expression> + +Form 2 syntax: +<LFM|SFM>{cond}<FD,EA> Fd, <count>, [Rn]{!} + +These instructions are fully implemented. They store/load three words +for each floating point register into the memory location given in the +instruction. The format in memory is unlikely to be compatible with +other implementations, in particular the actual hardware. Specific +mention of this is made in the ARM manuals. + +Floating Point Coprocessor Register Transfer Instructions (CPRT) +---------------------------------------------------------------- + +Conversions, read/write status/control register instructions + +FLT{cond}<S,D,E>{P,M,Z} Fn, Rd Convert integer to floating point +FIX{cond}{P,M,Z} Rd, Fn Convert floating point to integer +WFS{cond} Rd Write floating point status register +RFS{cond} Rd Read floating point status register +WFC{cond} Rd Write floating point control register +RFC{cond} Rd Read floating point control register + +FLT/FIX are fully implemented. + +RFS/WFS are fully implemented. + +RFC/WFC are fully implemented. RFC/WFC are supervisor only instructions, and +presently check the CPU mode, and do an invalid instruction trap if not called +from supervisor mode. + +Compare instructions + +CMF{cond} Fn, Fm Compare floating +CMFE{cond} Fn, Fm Compare floating with exception +CNF{cond} Fn, Fm Compare negated floating +CNFE{cond} Fn, Fm Compare negated floating with exception + +These are fully implemented. + +Floating Point Coprocessor Data Instructions (CPDT) +--------------------------------------------------- + +Dyadic operations: + +ADF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - add +SUF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - subtract +RSF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - reverse subtract +MUF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - multiply +DVF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - divide +RDV{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - reverse divide + +These are fully implemented. + +FML{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - fast multiply +FDV{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - fast divide +FRD{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - fast reverse divide + +These are fully implemented as well. They use the same algorithm as the +non-fast versions. Hence, in this implementation their performance is +equivalent to the MUF/DVF/RDV instructions. This is acceptable according +to the ARM manual. The manual notes these are defined only for single +operands, on the actual FPA11 hardware they do not work for double or +extended precision operands. The emulator currently does not check +the requested permissions conditions, and performs the requested operation. + +RMF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - IEEE remainder + +This is fully implemented. + +Monadic operations: + +MVF{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - move +MNF{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - move negated + +These are fully implemented. + +ABS{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - absolute value +SQT{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - square root +RND{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - round + +These are fully implemented. + +URD{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - unnormalized round +NRM{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - normalize + +These are implemented. URD is implemented using the same code as the RND +instruction. Since URD cannot return a unnormalized number, NRM becomes +a NOP. + +Library calls: + +POW{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - power +RPW{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - reverse power +POL{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - polar angle (arctan2) + +LOG{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - logarithm to base 10 +LGN{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - logarithm to base e +EXP{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - exponent +SIN{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - sine +COS{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - cosine +TAN{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - tangent +ASN{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - arcsine +ACS{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - arccosine +ATN{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - arctangent + +These are not implemented. They are not currently issued by the compiler, +and are handled by routines in libc. These are not implemented by the FPA11 +hardware, but are handled by the floating point support code. They should +be implemented in future versions. + +Signalling: + +Signals are implemented. However current ELF kernels produced by Rebel.com +have a bug in them that prevents the module from generating a SIGFPE. This +is caused by a failure to alias fp_current to the kernel variable +current_set[0] correctly. + +The kernel provided with this distribution (vmlinux-nwfpe-0.93) contains +a fix for this problem and also incorporates the current version of the +emulator directly. It is possible to run with no floating point module +loaded with this kernel. It is provided as a demonstration of the +technology and for those who want to do floating point work that depends +on signals. It is not strictly necessary to use the module. + +A module (either the one provided by Russell King, or the one in this +distribution) can be loaded to replace the functionality of the emulator +built into the kernel. |